theorem instFiatPointAtToParent
theorem instFiatPointAtToParent: ∀ (x t : Type) [FiatPoint.At x t], ContinuantFiatBoundary.At x t
theorem instFiatPointAtToParent
theorem instFiatPointAtToParent: ∀ (x t : Type) [FiatPoint.At x t], ContinuantFiatBoundary.At x t